Sampling device for multiple hearth furnace

ABSTRACT

A sampling device for removing a sample of a particulate solid material falling within a vessel and especially suited for use in obtaining a sample of a particulate material falling between the hearths of a multiple-hearth furnace includes an elongated cylindrical tubular member which extends through a wall of the vessel or furnace. The inner end of the tubular member is formed as an upwardly open and open-ended section disposed within the vessel or furnace to collect particulate solid material falling therein. A ram plate can be moved through the tubular member by means of a connecting rod projecting from the outer end of the sampling device and, on inward movement of the ram plate, material collected in a channel section of the device is pushed out of the open inner end of that section. On outward movement of the ram plate, the particulate material collected in the channel section is pushed outwardly by the ram plate through the tubular member for discharge therefrom into a sample-receiving container.

United States Patent [72] inventor William J. Lavender Edmonton, Alberta, Canada [21] Appl. No. 60,784 [22] Filed Aug. 4, 1970 [45] Patented Dec. 21, 1971 [73] Assignee Sherritt Gordon Mines Limited Toronto, Ontario, Canada [54] SAMPLING DEVICE FOR MULTIPLE HEAR'III FURNACE 9 Claims, 6 Drawing Figs.

[52] US. Cl....., 263/26,

' 73/421 R,263/1 [51] Int. Cl. F27b 1/10 [50] Field of Search 263/1, 26;

73/421 R,42i A [56] References Cited 7 UNITED STATES PATENTS 1,537,027 5/1925 Gleason et al. 263/1 1,811,920 6/1931 Dickson 263/26 3,464,271 9/1969 Ketelsen 73/421 Primary Examiner-J0hn J. Camby Attorneys--Frank l. Piper, Arne l. Fors and James T. Wilbur ABSTRACT: A sampling device for removing a sample of a particulate solid material falling within a vessel and especially suited for use in obtaining a sample of a particulate material falling between the hearths of a multiple-hearth furnace includes an elongated cylindrical tubular member which extends through a wall of the vessel or furnace. The inner end of the tubular member is formed as an upwardly open and openended section disposed within the vessel or furnace to collect particulate solid material falling therein. A ram plate can be moved through the tubular member by means of a connecting rod projecting from the outer end of the sampling device and, on inward movement of the ram plate, material collected in a channel section of the device is pushed out of the open inner end of that section. On outward movement of the ram plate, the particulate material collected in the channel section is pushed outwardly by the ram plate through the tubular member for discharge therefrom into a sample-receiving container.

PATENTEMsczvm 3,628,777,

SHEET 2 BF IN VE N TOR WILI, IAM J. LAVENDER SAMPLING DEVICE FOR MULTIPLE IIEARTH FURNACE The present invention relates to sampling devices and more particularly to sampling devices which are particularly suited for use in removing samples of particulate solid material from a vessel within which the material is falling. The sampling device of this invention is especially suited for sampling particulate solid material falling between the adjacent hearths of multiple-hearth furnaces.

During the operation of a multiple-hearth furnace, it is frequently desired to-obtain samples of the solid particulate material moving between the hearths of the furnace for the purpose of determining the rate of change of chemical state of the material passing through the furnace at various levels within the furnace. Naturally, it is desirable that such samples be obtained without disturbing the operating conditions existing within the furnace.

It is accordingly a principal object of this invention to provide a sampling device which can be installed in the wall of a vessel, such as a multiple-hearth furnace, within which a particulate solid material is falling, for the purpose of withdrawing samples of the particulate solid material from within the vessel without affecting the conditions existing within the vessel.

Another object of this invention is to provide a sampling device of the type indicated and which sampling device is characterized by its efficiency and ease of operation and by its simplicity of construction.

' Other objects of the invention will become apparent as the description herein proceeds.

In its broadest scope, the present invention provides a sampling device for removing a sample of solid particulate material from a vessel within which particulate material is falling, which sampling device comprises an elongated tubular member of substantially constant internal transverse configuration throughout its length and which is adapted to be secured in an opening extending through a wall of the vessel so as to project inwardly and outwardly through the vessel wall and terminating within the vessel in an upwardly open and open-ended channel section for receiving particulate material falling within the vessel, a sample discharge outlet communicating with the interior of said elongated tubular member and adapted to be disposed outwardly of the vessel wall for the discharge of particulate solid material from within said elongated tubular member, a ram plate having a peripheral configuration corresponding to said internal transverse configuration of said elongated tubular member for free longitudinal movement within said elongated tubular member as well as within said open-ended channel section thereof, and an elongated connecting rod secured at its inner end to said ram plate and having an outer end extending outwardly from within said elongated tubular member for moving said ram plate axially within said elongated tubular member, whereby, when said' sampling device is secured in an opening in a vessel wall, solid particulate material collected in said upwardly open and openended channel section of said elongated tubular member can be returned to the vessel through said open end of said channel section by inward movement of said connecting rod with conjoint inward movement of said ram plate through said channel section toward said open end thereof and whereby solid particulate material collected in said upwardly open and open-ended channel section can be removed from said vessel by outward movement of said connecting rod with conjoint outward movement of said ram plate outwardly from said open end of said channel section to push such solid particulate material outwardly through said elongated tubular member to said sample discharge outlet thereof.

As already indicated herein, an important object of this invention is to provide a sampling device particularly suited for installation in a wall of a multiple-hearth furnace and, in accordance with another important feature of this invention, a sampling device as hereinbefore defined can usefully be mounted on a multiple-hearth furnace so that the upwardly open channel section of the elongated tubular member of the sampling device is disposed within the furnace so as to receive particulate solid material falling between two hearths of the furnace.

In accordance with another important feature of this invention, a sampling device as hereinbefore defined can optionally be provided with means whereby a particulate solid material sample obtained using the sampling device can be maintained under a non-reactive atmosphere during its removal from a multiple-hearth furnace.

Other features and advantages of the invention will become apparent as the description herein proceeds.

The invention will now be described merely by way of illustration with reference to the accompanying drawings in which:

FIG. 1 is a fragmentary somewhat schematic vertical sectional view through a conventional multiple-hearth furnace showing one embodiment of a sampling device in accordance with this invention installed in a wall of the furnace;

FIG. 2 is an enlarged and fragmentary perspective view of the sampling device shown in FIG. I with certain internal components of that device shown in phantom outline;

FIG. 3 is a vertical sectional view through the sampling device of FIG. 2 when taken along the longitudinal axis of that device;

FIG. 4 is a vertical sectional view through the sampling device of FIGS. 2 and 3 when taken as indicated by the arrows 4-4 of FIG. 2;

FIG. 5 is an enlarged perspective view of a ram plate structure provided in the sampling device of FIGS. 2 to 4 and also showing in part a connecting rod of the sampling device; and

FIG. 6 is an end elevation of the inner channel section of the sampling device of FIGS. 2 to 4 when viewed as indicated by the arrows 66 of FIG. 3.

There is shown somewhat fragmentarily at 10 in FIG. 1 of the accompanying drawings, a Nichols-l-lerreshoff multiplehearth furnace of conventional construction. The furnace 10 includes a number of annular hearths, such as the hearths II, 12, 13 and 14 suitably supported on the outer wall 17 of the furnace. A drive shaft lfl'extends upwardly through generally central openings in the hearths 11 through 14 and has suitably mounted thereon a plurality of rabble arms 19 and 20. It will be seen from FIG. 1 that alternate hearths such as hearths 12 and 14 are provided with central openings 21 which are larger than central openings 22 provided in the intermediate hearths, such as hearths 11 and 13. The hearths l1 and 13 are, however, formed with openings 23 near the outer furnace wall 17 for the passage of particulate material therethrough.

In a known furnace of this type, a particulate feed material is charged into the top of the furnace 10 and moves downwardly through that furnace countercurrently to an upwardly flowing gas stream so as to react with the gas. One typical application for such a,multiple-hearth furnace and in which the use of a sampling device in accordance with the present invention is particularly advantageous is in the roast reduction of nickel-containing laterite ores.

During operation of the furnace 10, the particulate solid material introduced into the upper end thereof is moved inwardly by the rabble arms 20 to the central openings 21 in the hearths 12 and 14 to fall through such openings 21 onto the underlying hearths, such as hearths l1 and 13 on which it is then moved radially outwardly by the rabble arms 19. The material then falls through the aforementioned openings 23 onto the respective ones of the hearths, such as hearths l2 and 14, disposed therebelow. In this way, the feed material progressively moves to a discharge outlet at the bottom of the furnace.

The desired chemical conversion, for example, a reduction in the aforementioned case of the roast reduction of laterite ores, takes place progressively as the material passes downwardly through the furnace 10. As already indicated, it is an important object of this invention to provide a sampling device for removing a particulate solid material for sampling purposes from a vessel within which the material is falling. One embodiment of a sampling device in accordance with this invention is shown generally at 24 in FIG. 1 as being mounted on the multiple-hearth furnace for the purpose of allowing a sample of the material falling through one of the openings 23 in the hearth 11 onto the hearth 12 disposed immediately below the hearth 11 to be obtained and removed from the furnace 10 when so required. Analysis of the sample can then be used, for example, for determining operating parameters such as the degree or reduction, oxidation, dehydration etc., of the furnace 10.

Referring now in greater detail to the specific construction shown in the accompanying drawings for the sampling device 24, it will be seen that this sampling device 24 includes an elongated inner tubular member 26 having a generally cylindrical internal configuration. The elongated tubular member 26 is coaxially disposed within a larger diameter outer cylindrical member 27 which is somewhat shorter than the inner member 26. The ends of the outer cylinder 27 are closed by the inner and outer annular end walls 28 and 29 respectively to define a closed annular cooling chamber 30.

An annular mounting flange 31 is suitably secured, for example, by welding as at 31 (FIG. 3) around the outer cylinder 27 slightly inwardly of the outer end of that cylinder and includes a number of angularly spaced-apart holes 33 through which bolts 34 can be inserted to hold the sampling device 23 firmly in position in an opening 36 (FIG. 3) extending through the wall 17 of the furnace 10.

In accordance with a particularly useful feature of this invention, radially extending couplings 38 and 39 are usefully provided through the wall of the cylindrical member 27 outwardly of the mounting flange 31 for the supply and discharge of a cooling liquid such as water into and out of the annular chamber 30. Hoses 40 and 41 are shown in FIGS. 1 and 2 of the drawings as being connected to the couplings 38 and 39 respectively for these purposes.

Within the furnace, inner cylindrical member 26 is formed as an open-topped channel section generally indicated at 44 and including a semicylindrical lower portion 45 and upstanding sidewalls 46 and 47 (FlG. 6). It should also be noted that, in accordance with an important feature of this invention, the channel section 44 is formed with an open inner end indicated at 48. The reason for adopting this particular construction will become apparent as the description herein proceeds.

Referring again to FIG. I, the upwardly open and openended channel section 44 of the inner cylindrical member 26 is disposed below one of the aforementioned openings 23 in the hearth 11 so that particulate solid material falling through that opening 23 will be received or collected within the channel section 44 of the sampling device 24.

At the outer end of the inner tubular member 26, there is provided a nipple 50 secured, for example, by welding as at 51, to the undersurface of the tubular member 26 for the purpose of discharging sampled particulate material from within that member 26 in a manner which will be more fully understood as the description herein proceeds. It can, however, be noted that, in the particular construction illustrated in the accompanying drawings, the nipple 50 is threaded at 52 so as to have a small sample-receiving cylinder 53 detachably screwed thereon for the purpose of receiving the sample.

A ram plate structure generally indicated at 55 (FIGS. 3 and 5) is provided for emptying the channel section 44 as well as for pushing a sample of the particulate material from within the channel section 44 outwardly through the tubular member 26 to the sample discharge outlet constituted by the nipple 50. The ram plate structure 55 shown in the accompanying drawings includes a generally circular plate 56 having a diameter which approximates the internal diameter of the elongated tubular member 26 so as to be free for longitudinal or axial movement within that member. The plate is secured to an elongated connecting rod 60 which extends through the elongated tubular member 26 and projects from the outer end of member 26. Two short rods 61 and 62 are suitably secured, for example, by welding, to the rod 60 near the outer end thereof to provide a handle by means of which the ram plate structure 55 may be moved longitudinally within the tubular member 26. A washer 63 is welded on the inner sides of the handle rods 61 and 62 for abutment with an end cap 64 threaded onto the outer end of the tubular member 26. Such abutment restricts inward movement of the connecting rod 60 and consequently of the ram plate structure 55 secured thereto.

A generally cylindrical plug 65 having an axial hole for the free passage therethrough of the connecting rod 60 and an annular lip 66 for engagement between the outer end of the tubular member 26 and the inner surface of the cap 64 is disposed within the outer end of the tubular member 26 and serves to provide improved gas sealing for the tubular member 26 for a reason which will be explained as the description herein proceeds.

A nipple 68 is secured, for example, by welding, to the tubular member 26 in general proximity to the outer end thereof and this nipple 68 is shown in FIGS. 1 and 2 of the accompanying drawings as having a hose 69 suitably coupled thereto for the introduction of an inert gas, such as nitrogen, into the tubular member 26.

In use, the aforementioned hose 40 is coupled to a supply of cooling water which water passes into the annular chamber 30 from which it is discharged through the hose 4!. The hose 69 is coupled to a suitable inert gas supply, for example, to a cylinder of nitrogen, and the connecting rod 60 is then pulled outwardly in the direction by the arrow A (FIG. 3) until the ram plate assembly 55 is disposed near the discharge outlet nipple 50. In this way, any solid material present in the tubular member 26 is emptied from that member through the nipple 50 and into sample collecting cylinder 53.

When it is desired to collect a sample of the particulate material falling through the respective opening 23 of the hearth ll of the furnace 10, the connecting rod 60 is pushed inwardly by the handle rods 61 and 62 so that the ram plate structure 55 moves inwardly through the tubular member 25 as well as through the channel section 44 of that member to push any particulate material previously collected in the channel section 44 out of that section through the open inner end thereof. Such discarded material falls onto the next lower hearth, i.e., hearth 12, of the furnace 10. Material issuing from the hole 23 is then received in the channel section 44 and, after any desired period of time, the connecting rod 60 is pulled outwardly in the direction opposite to that indicated by the arrow A to cause the ram plate structure 55 to move outwardly through the channel section 44 and through the tubular member 26 and to push the material collected in the channel section 44 through the tubular member 26 so that such material falls through the nipple 50 into the sample-receiving cylinder 53.

The provision of the nipple 68 and of the inert gas supply hose 69 as already described herein as particularly advantageous in circumstances where it is desired to obtain a sample of particulate material from within the furnace MD is essentially the same chemical state as that in which it was present in the furnace. For example, in many circumstances, contact of the particulate material from within such a furnace with air can result in oxidation of such material. Such undesired modification of the sample material is substantially completely avoided in accordance with this particularly advantageous feature of the invention by withdrawing the sample under an inert gas atmosphere using the sampling device 10 already described herein. Naturally, in circumstances where the material being sampled is unaffected by exposure to air, the provision of such an inert atmosphere within a sampling device according to this invention is unnecessary. Similarly, the provision of the annular cooling chamber 30 is required only where the temperatures involved are such that such cooling is required or desirable.

Iclaim:

1. A sampling device for removing a sample of solid particulate material. from a vessel within which said solid particulate material is falling, which sampling device comprises an elongated tubular member of substantially constant internal transverse configuration through out its length and which is adapted to be secured in an opening extending through a wall of said vessel so as to project inwardly and outwardly through said vessel wall and terminating within said vessel in anupwardly open and open-ended channel section for receiving particulate material falling within said vessel, a sample discharge outlet communicatingwith the interior of said elongated tubular member and adapted to be disposed outwardly of the vessel wall for the discharge of particulate material from within said elongated tubular member, a ram plate having a peripheral configuration corresponding to said internal transverse configuration of said elongated tubular member for free longitudinal movement within said elongated tubular member as well as within said open-ended channel section thereof, and an elongated connecting rod secured at its inner end to said ram plate and having an outer end extending outwardly from within said elongated tubular member for moving said ram plate longitudinally within said elongated tubular member, whereby when said sampling device is secured in an opening in a vessel wall, solid particulate material collected in said upwardly open and open-ended channel section of said elongated tubular member can be removed from said tubular member through said open end of said channel section by inward movement of said connecting rod with conjoint inward movement of said ram plate through said channel section towards said open end thereof and whereby solid particulate material collected in said upwardly open and open-ended channel section can be removed from said vessel by outward movement of said connecting rod with conjoint outward movement of said ram plate outwardly from said open end of said channel section of said elongated tubular member to push such solid particulate material outwardly through said elongated tubular member to said sample discharge outlet thereof.

2. A sampling device as claimed in claim 1 which device additionally comprises a cooling jacket mounted around said elongated tubular member to define a closed elongated annular chambertherearound, mounting means secured to said cooling jacket for securing said sampling device within an opening in the wall of a vessel, fluid supply and discharge conduits communicating with said elongated annular chamber for the supply and discharge of cooling liquid into and out of said annular chamber.

3. A sampling device as claimed in claim 1 in which said sample discharge outlet is adapted to have a sample-receiving container detachably secured thereto in a generally gastight manner and which sampling device additionally comprises gas supply means communicating with the interior of said elongated tubular member for the supply of a nonreactive gaseous material into said elongated tubular member whereby solid particulate material withdrawn from said vessel through said elongated tubular member can be maintained in an unmodified form.

4. A sampling device as claimed in claim 1 in which said elongated tubular member has a generally circular internal transverse configuration and in which said upwardly open and open-ended channel section thereof has a generally semicircular internal transverse configuration in a lower portion thereof with integrally formed upstanding sidewalls.

5. A sampling device as claimed in claim which additionally comprises a stop member adapted to prevent inward movement of said ram plate beyond said inner end of said upwardly open and open-ended channel section of said elongated tubular member.

6. A multiple-hearth furnace in which in use solid particulate material falls between adjacent vertically spaced-apart hearths and which furnace additionally includes a sampling device which in turn comprises an elongated tubular member of substantially constant internal transverse configuration throughout its length and which is secured within an opening extending through a wall of said furnace so as to project inwardly and outwardly through said wall of said furnace to terminate within said furnace in an upwardlyppen and open ended channel section disposed between ad acent hearths of said furnace for receiving solid particulate material falling between said hearths, a sample discharge outlet communicating with the interior of said elongated tubular member and disposed outwardly of said furnace wall for the discharge of solid particulate material from within said elongated tubular member, a ram plate having a peripheral configuration corresponding to said internal transverse configuration of said elongated tubular member for free longitudinal movement within said elongated tubular member as well as within said open-ended channel section thereof, and an elongated connecting rod secured at its inner end to said ram plate and having an outer end extending outwardly from within said elongated tubular member for moving said ram plate axially within said elongated tubular member, whereby solid particulate material collected in said upwardly open and open-ended channel section of said elongated tubular member can be returned to said furnace through said open end of said channel section of said elongated tubular member by inward movement of said connecting rod with conjoint inward movement of said ram plate through said channel section towards said open end thereof and whereby solid particulate material collected in said upwardly open and open-ended channel section can be removed from said furnace by outward movement of said connecting rod with conjoint outward movement of said ram plate outwardly from said open end of said channel section to push such solid particulate material outwardly through said elongated tubular member to said sample discharge outlet of said sampling device.

7. A multiple-hearth furnace as claimed in claim 6 in which said sample discharge outlet of said sampling device is adapted to have a sample-receiving container detachably secured thereto in a generally gastight manner and which sampling device additionally comprises a gas supply means communicating with the interior of said elongated tubular member for the supply of a nonreactive gaseous material into said elongated tubular member whereby solid particulate material withdrawn from said furnace through said sampling device can be maintained in an unmodified form.

8. A multiple-hearth furnace as claimed in claim 7 in which said sampling device additionally comprises a cooling jacket mounted around said elongated tubular member to define a closed elongated annular chamber therearound, mounting means secured to said cooling jacket and securing said sampling device within said opening in said wall of said furnace, fluid supply and dischargeconduits communicating with said elongated annular chamber for the supply and discharge of a cooling liquid into and out of said annular chamber.

9. A multiple-hearth furnace as claimed in claim 8 in which said elongated tubular member of said sampling device has a generally circular internal transverse configuration and in which said upwardly open and open-ended section thereof has a generally semicircular internal transverse configuration in a lower portion thereof with integrally formed upstanding sidewalls. 

1. A sampling device for removing a sample of solid particulate material from a vessel within which said solid particulate material is falling, which sampling device comprises an elongated tubular member of substantially constant internal transverse configuration through out its length and which is adapted to be secured in an opening extending through a wall of said vessel so as to project inwardly and outwardly through said vessel wall and terminating within said vessel in an upwardly open and open-ended channel section for receiving particulate material falling within said vessel, a sample discharge outlet communicating with the interior of said elongated tubular member and adapted to be disposed outwardly of the vessel wall for the discharge of particulate material from within said elongated tubular member, a ram plate having a peripheral configuration corresponding to said internal transverse configuration of said elongated tubular member for free longitudinal movement within said elongated tubular member as well as within said open-ended channel section thereof, and an elongated connecting rod secured at its inner end to said ram plate and having an outer end extending outwardly from within said elongated tubular member for moving said ram plate longitudinally within said elongated tubular member, whereby when said sampling device is secured in an opening in a vessel wall, solid particulate material collected in said upwardly open and open-ended channel section of said elongated tubular member can be removed from said tubular member through said open end of said channel section by inward movement of said connecting rod with conjoint inward movement of said ram plate through said channel section towards said open end thereof and whereby solid particulate material collected in said upwardly open and open-ended channel section can be removed from said vessel by outward movement of said connecting rod with conjoint outward movement of said ram plate outwardly from said open end of said channel section of said elongated tubular member to push such solid particulate material outwardly through said elongated tubular member to said sample discharge outlet thereof.
 2. A sampling device as claimed in claim 1 which device additionally comprises a cooling jacket mounted around said elongated tubular member to define a closed elongated annular chamber therearound, mounting means secured to said cooling jacket for securing said sampling device within an opening in the wall of a vessel, fluid supply and discharge conduits communicating with said elongated annular chamber for the supply and discharge of cooling liquid into and out of said annular chamber.
 3. A sampling device as claimed in claim 1 in which said sample discharge outlet is adapted to have a sample-receiving container detachably secured thereto in a generally gastight manner and which sampling device additionally comprises gas supply means communicating with the interior of said elongated tubular member for the supply of a nonreactive gaseous material into said elongated tubular member whereby solid particulate material withdrawn from said vessel through said elongated tubular member can be maintained in an unmodified form.
 4. A sampling device as claimed in claim 1 in which said elongated tubular member has a generally circular internal transverse configuration and in which said upwardly open and open-ended channel section thereof has a generally semicircular internal transverse configuration in a lower portion thereof with integrally formed upstanding sidewalls.
 5. A sampling device as claimed in claim which additionally comprises a stop member adapted to prevent inward movement of said ram plate beyond said inner end of said upwardly open and open-ended channel section of said elongated tubular member.
 6. A multiple-hearth furnace in which in use solid particulate material falls between adjacent vertically spaced-apart hearths and which furnace additionally includes a sampling device which in turn comprises an elongated tubular member of substantially constant internal transverse configuration throughout its length and which is secured within an opening extending through a wall of said furnace so as to project inwardly and outwardly through said wall of said furnace to terminate within said furnace in an upwardly open and open-ended channel section disposed between adjacent hearths of said furnace for receiving solid particulate material falling between said hearths, a sample discharge outlet communicating with the interior of said elongated tubular member and disposed outwardly of said furnace wall for the discharge of solid particulate material from within said elongated tubular member, a ram plate having a peripheral configuration corresponding to said internal transverse configuration of said elongated tubular member for free longitudinal movement within said elongated tubular member as well as within said open-ended channel section thereof, and an elongated connecting rod secured at its inner end to said ram plate and having an outer end extending outwardly from within said elongated tubular member for moving said ram plate axially within said elongated tubular member, whereby solid particulate material collected in said upwardly open and open-ended channel section of said elongated tubular member can be returned to said furnace through said open end of said channel section of said elongated tubular member by inward movement of said connecting rod with conjoint inward movement of said ram plate through said channel section towards said open end thereof and whereby solid particulate material collected in said upwardly open and open-ended channel section can be removed from said furnace by outward movement of said connecting rod with conjoint outward movement of said ram plate outwardly from said open end of said channel section to push such solid particulate material outwardly through said elongated tubular member to said sample discharge outlet of said sampling deviCe.
 7. A multiple-hearth furnace as claimed in claim 6 in which said sample discharge outlet of said sampling device is adapted to have a sample-receiving container detachably secured thereto in a generally gastight manner and which sampling device additionally comprises a gas supply means communicating with the interior of said elongated tubular member for the supply of a nonreactive gaseous material into said elongated tubular member whereby solid particulate material withdrawn from said furnace through said sampling device can be maintained in an unmodified form.
 8. A multiple-hearth furnace as claimed in claim 7 in which said sampling device additionally comprises a cooling jacket mounted around said elongated tubular member to define a closed elongated annular chamber therearound, mounting means secured to said cooling jacket and securing said sampling device within said opening in said wall of said furnace, fluid supply and discharge conduits communicating with said elongated annular chamber for the supply and discharge of a cooling liquid into and out of said annular chamber.
 9. A multiple-hearth furnace as claimed in claim 8 in which said elongated tubular member of said sampling device has a generally circular internal transverse configuration and in which said upwardly open and open-ended section thereof has a generally semicircular internal transverse configuration in a lower portion thereof with integrally formed upstanding sidewalls. 